Lady Gaga remembered watching the Twin Towers crumble from the roof of her high school, the Convent of the Sacred Heart on the Upper East Side, and hailed Osama bin Laden’s death as “an historical moment in the fight against hatred” in a radio interview. She remembered that her dad, Joseph, walked his then- 15-year-old daughter home from school, and together they later waited 10 desperate hours to hear from her mom, Cynthia, who worked across the street from the World Trade Center. “The whole city was covered in ashes,” Gaga told radio host Toby Knapp in an interview slated to air today on Washington, DC’s Hot 99.5. Gaga said she had mixed emotions when she learned bin Laden was dead. “It’s a difficult thing — nobody wants to celebrate anyone’s death,” Gaga said. “But I know it was something that meant a lot to the people of New York, especially those who lost lives that day.”